Florida Republican Sen. Mel Martinez, who has already said he will not run again in 2010, told his staff today that he will not return to the Senate after the August recess, and will instead retire.

Martinez planned a Friday afternoon announcement in Florida to officially divulge his plans. The sources spoke on condition of anonymity because they were not authorized to do so before his announcement.

This means that Florida's Republican Governor Charlie Crist, who is running for Martinez' Senate seat in 2010, will get to choose Martinez' interim replacement.

"It's a deeply personal decision that he will expand on later today. He decided it's time to move to another stage of his life,'' a source familiar with the situation told the Miami Herald.

Crist isn't saying much on the subject. When asked by the Los Angeles Times for a comment, he said, "We'll talk later today. I've got to get to McDill Air Force Base." Then he waved and went back inside the governor's mansion.